Offshore oil well installation



Sept. 3@, 1953 W. R. cox, JR, ETAL 5 9 OFFSHORE OIL WELL INSTALLATION IFiled March 5, 1956 2 Sheets-Sheet 1 INVENTORS wacox, JR. Rd. HOWE THEIRAGENT Sept. 30, 1958 w. R. cox, JR, EFAL 2,854,215

OFFSHORE OIL WELL INSTALLATION Filed March 5, 1956 2 Sheets-Sheet 2 [KQOO 35- in, I m

H3 33\ wzAm INVENTORS W.R. cox, JR. R. J. HOWE nite orrsnonn on WELLrNsrALLArtoN Wiiiiam R. Con, 31:, Corpus Christi, Tex., and Richard J.Howe, Dayton, @hio, assignoi's to Shell Development Company, New York,N. Y., a corporation of Delaware Application March 5, 1256, SerialNo.569,332

Claims. ((1255-25) This invention relates to oil well drilling andproduction equipment for use at offshore locations and pertains moreparticularly to a method and apparatus for installing or repairingwellhead equipment positioned underwater.

in their search for new oil fields, many oil drilling and producingcompanies are operating in offshore locations where wells are beingdrilled in 5 to 100 feet of water. The present procedure of drilling awell at an offshore location is either to provide a stationary platformat that location or to sink a submersible barge there for the durationof the drilling operations. After drilling a well from a permanentplatform, at least a portion of the platform is left in place adjacentthe wellhead for servicing the well. When drilling from a submersiblebarge, it is necessary, after the drilling has been completed, toprovide a small platform or framework about the casing and wellhead fromwhich the well may be serviced. The platforms left about a producingwell also protect the wellhead and the casing extending from the oceanfloor to the surface and above from collision with boats.

The production platforms that are left about a wellhead are normallyquite expensive, ranging in price, depending upon size and uponlocation, from $10,000 to $200,000. The platforms, together with thewellhead which they surround and/ or support, constitute a hazard tonavigation, and as the offshore oil fields are being rapidly developed,dozens or hundreds of these wellhead platforms pose a considerableproblem to navigation.

it is therefore a primary object of the present invention to provide amethod and apparatus for drilling wells and subsequently providing awellhead structure and/or apparatus which is secured to an oil wellcasing and production tubing below the surface of the water.

Another object of this invention is to provide wellhead structure andapparatus adapted to be mounted on a well casing below the surface ofthe water in a water-tight manner and at a level at which it will not besubject to collision with boats.

A further object of this invention is to provide apparatus for servicingthe wellhead installation positioned well below the surface of thewater.

These and other objects of this invention will be understood from thefollowing description taken with reference to the drawings, wherein:

Figure l is a diagrammatic elevation view taken partially in crosssection, of an underwater wellhead installation comprising a fluidtightchamber;

Figures 2, 3 and 4 are diagrammatic elevation views illustratingsuccessive steps of an underwater method for gaining access to thewellhead assembly in the fluidtight chamber of Figure l.

Patented Sept. 30, 1958 Referring to Figure 1, a completed underwaterwell installation is diagrammatically illustrated as comprising a largediameter conductor guide pipe 11 on which is positioned a preferablycylindrical housing 12 normally closed at the top in a fluidtight mannerby a cover 13. The conductor guidepipe 11 is of a type 'generally'usedin drilling offshore wells and may be 2 or 3 feet or more in diameter.In normal drilling operations a conductor guide pipe of this type iswashed or driven 40 feet or more into the ocean floor, while the upperend thereof extends above the water line. The well is then drilledthrough this conductor guide pipe. In the present invention theconductor guide pipe 11 may only extend a short distance above the mudline 14, but may be extended to a substantial distance above the mudline in very deep water locations.

Prior to driving the conductor guide pipe 11 into the sub-soil, thecylindrical housing 12 is secured to the top thereof in a fiuidtightmanner, as by welding at 15. A cover 13 may be bolted to the top of thehousing 12 in a preferably fluidtight manner. As a safety precaution,the cover may be provided with a pressure indicator 40 which is incommunication with the chamber 16 within the housing 12. Thus, beforeremoving the cover 13 from the housing 12, the pressure in said housingmay be checked to make sure that it is at a value which permits removalof the cover. Also, it may be desired to pressurize the housing after itis closed to keep any mud and/ or sea water out. A valved opening in thecover may be provided for this purpose.

As shown in Figure 2, the cover 13 is provided with two or more guidebars 17 which slope upwardly from the edges of the cover to the centerthereof and provide an upwardly-pointing centering guide by which theopen end of a cylindrical caisson may be aligned with the housing 12 sothat it may be lowered until it surrounds the housing, as illustrated.Fixedly secured to the outer wall of the housing 12 are suitable caissonsupport means such as bracket or flange means 19.

The caisson 18 is of a length sufficient to extend from the fiange means19 on the housing 12 to a point above the water level 20. The innerdiameter of the caisson 18 is just slightly greater than the outerdiameter of the housing 12 so that a substantially tight fit occursbetween the two elements when they are positioned as shown in Figure 2.Preferably, the inner walls and/or the lower end of the caisson 18 areprovided with suitable sealing means 21 such, for example, as cuppackers, O-ring seals, or any other suitable type of packers, seals orgaskets. If necessary, the sealing means may be of an inflatable type asshown at 33 in Fig. 3, which is adapted to be inflated by pneumatic orhydraulic pressure supplied through a conduit 34 from the surface. It isto be understood that the sealing means 21 illustrated as provided onthe inner surface and bottom edge of the caisson 18 could be providedalternatively on the outer surface of the housing 12 or the top surfaceof the flange means 19. The inner wall of the caisson 18 is preferablyprovided with a ladder or steps 22 by which an operator can lowerhimself to the bottom of the caisson.

The interior of the housing 12 is normally from 6 to 12 feet indiameter, or large enough to enclose the necessary connections andfittings of a wellhead assembly normally secured to the top of a wellcasing 23, and comprising a control valve 24, choke '25 and pressuregauge 26. A

fluid can be pumped when it is desired to kill a well.

The production line 28 leads from the wellhead assembly through the wallof the housing 12 in a fluidtight manner and thence along the oceanfloor or to the surface in any desired manner.

Before the caisson 18 is removed from the housing 12, as shown in Figure1, a buoy line 29 is secured to the'top of the cover 13 so that itextends up to a marker buoy 36 which is adapted to float on the surfaceof the water substantially above the wellhead installation. A protectingring 31 for the top'ssurface of the flange means 19 may be provided topreventmud from settling thereon and interfere with the positioning of acaisson. The ring can be removed by means of a cable 32 running up tothe buoy 30. When operating in deep water, say at 100 feet, the top :ofthe housing 12 would preferably be positioned below the surface of thewater 20 at a sufiicient depth, say feet, so that ships can safely passover the wellhead Without causing any damage.

Whenever, it becomes necessary to service an underwater wellinstallation, as illustrated in Figure l, a service boat 36 (Fig. 3)transports the caisson 18 to the wellhead installation and lowers itover the marker buoy 30 and down onto the housing 12 as shown in Figure2. A hose 37 may be dropped from the service boat so that the water inthe caisson above the cover 13 may be pumped out. The hose 37 isconnected to a suitable pump (not shown) which is either carried on theservice boat or is lowered down into the caisson. After the caisson isemptied, the marker buoy. and its line may be removed as shown in Figure3. The cover 13 is then unfastened and removed, and the chamber 16within the housing 12 is opened so that the wellhead assembly may beserviced, as shown in Figure 4.

in drilling a well to which a wellhead of the present invention isconnected, the caisson 18 would be mounted on the housing 12 prior toforcing the housing and its conductor pipe 11 below the surface of thewater. Thus, during drilling operations the conductor pipe 11, housing12 and caisson 18 would take the form'of that shown in Figure 4 withoutthe well'casing 23 or its wellhead assembly in place. If. desired, theconductor pipe 11 could extend up through the housing and all the way tothe top of the caisson, or above, during drilling operations and then becut off flush with the bottom of the chamber 16 Within the housing 12after the drilling operations were completed. After the well is drilledand easing set, the

wellhead assembly is lowered within the caisson and attached in theusual manner. The housing is then closed and the caisson 18 filled withwater prior to removal. The caisson 18 is substantially flooded withwater in a similar manner prior to the removal of the caisson after wellservicing operations have been conducted.

We claim as our invention:

1. An underwater well installation comprising in combination a wellcasing extending into the ocean floor, a well-head assembly mounted onthe top of said casing at a level below the surface of the water andabove the ocean floor, a large diameter guide pipe surrounding saidcasing, the lower end of said guide pipe being positioned in said oceanfloor, a housing fixedly secured on the top of the guide pipe in afluidtight manner surrounding said wellhead assembly, removable covermeans closing the top of said housing in a fluidtight manner, aremovable caisson adapted to surround at least a portion of said housingin fluidtight contact therewith, said caisson extending from saidhousing to above the surface of the water and being freely removablefrom said housing at this point, and support means on said housing forsupporting the lower end of said caisson.

2. An underwater well installation comprising in combination a wellcasing extending into the ocean floor, a well-head assembly mounted onthe top of said casmg at a level below the surface of the waterand abovethe ocean floor, a large diameter guide pipe surrounding said casing,the lower end of said guide pipe being positioned into said ocean floor,a cylindrical housing fixedly secured on the top of the guide pipe in afluidtight manner surrounding said well-head assembly, cover meansclosing the top of said housing in a fluidtight manner, a removablecaisson adapted to surround at least a portion of said housing influidtight contact therewith, said caisson extending from said housingto above the surface of the water and being freely removable from saidhousing at this point, support means on said housing for supporting thelower end of said caisson above the ocean floor, and sealing meanscarried between said housing'and the lower portion of said caissonforming a watertight seal therebetween, said cover means being adaptedto be raised and lowered through said caisson on top of said housing,and said well-head assembly being adapted to be installed and servicedin said housing through said caisson.

3. An underwater well installation comprising in combination a wellcasing extending into the ocean floor, a well-head assembly mounted onthe top of said casing at a level below the surface of the water andabove the ocean floor, a large diameter guide pipe surrounding saidcasing, the lower end of said guide pipe being forced into i said oceanfloor, a cylindrical housing fixedly secured on the top of the guidepipe in a fluidtight manner surrounding said well-head assembly, covermeans closing the top of said housing in a fluidtight manner, aproduction conduit extending through the wall of said housing in a fluidtight manner and in communication between the wellhead assembly and thespace outside the housing for transporting production fluid away fromthe well, a removable caisson adapted to surround at least a portion ofsaid housing in fluidtight contact therewith, said caisson extendingfrom said housing to above the surface of the water and being freelyremovable from said housing at this point, outwardly-extending flangemeans on said housing above said production conduit for supporting thelower end of said caisson, and sealing.

means carried between said housing and the lower portion of said caissonforming a watertight seal therebetween, said cover means being adaptedto be raised and 1 lowered through said caisson on top of said housing,and said well-head assembly being adapted to be installed and servicedin said housing through said caisson.

4. An underwater well installation comprising in combination a wellcasing extending into the ocean floor, a well-head assembly mounted onthe top of said casing at a level below the surface of the water andabove the ocean floor, a large diameter guide pipe surrounding saidcasing, the lower end of said guide pipe being forced into said oceanfloor, a cylindrical housing fixedly secured on the top of the guidepipe in a fluidtight manner surrounding said well-head assembly, covermeans closing the top of said housing in a fluidtight manner, valvedconduit means through said cover means whereby said closed housing maybe pressurized, a removable caisson adapted to surround at least aportion of said housing in fluidtight contact therewith, said caissonextending from said housing to above the surface of the water and beingfreely removable from said housing at this point, support means on saidhousing for supporting the lower end of said caisson, and inflatablesealing means insertable between said housing and the lower portion ofsaid caisson for forming a' watertight seal therebetween, said covermeans being adapted to be raised and lowered through said caisson on topof said housing, and said well-head assembly being adapted to beinstalled and serviced in said housing through said caisson.

5. A method for drilling and producing wells in submerged areascomprising the steps of forcing a guide pipe into the bottom of a bodyof water, forming at the upper part of said guide pipe and in registertherewith a tubular housing of enlarged diameter, said housing beingpositioned substantially below the surface of water, surrounding saidhousing with a caisson sealed in fiuidtight external engagementtherewith, said caisson extending to the surface, drilling a well fromthe surface through said caisson, said housing and said guide pipe,removing the drilling tools therefrom, providing the well With thedesired casing and tubing, said casing and tubing extending from desiredWell depths to said housing, lowering through said caisson a Well-headassembly and installing it on top of the casing Within said housing,establishing a well fluid flow between said assembly and the spaceoutside of said References Cited in the file of this patent UNITEDSTATES PATENTS 272,722 Loud Feb. 20, 1883 1,262,075 McCutcheon Apr. 9,1918 2,171,672 Plummer Sept. 5, 1939 2,534,480 Shannon Dec. 19, 19502,783,970 Gillespie Mar. 5, 1957

1. AN UNDERWATER WELL INSTALLATION COMPRISING IN COMBINATION A WELLCASING EXTENDING INTO THE OCEAN FLOOR, A WELL-HEAD ASSEMBLY MOUNTED ONTHE TOP OF SAID CASING AT A LEVEL BELOW THE SURFACE OF THE WATER ANDABOVE THE OCEAN FLOOR, A LARGE DIAMETER GUIDE PIPE SURROUNDING SAIDCASING, THE LOWER END OF SAID GUIDE PIPE BEING POSITIONED IN SAID